[463] WIP sketch ETL job

...signalboost/signalc/backfill/signaldToSignalc/Migrator.kt

...t/signalc/backfill/signaldToSignalc/SignalcAccountData.kt

...t/signalc/backfill/signaldToSignalc/SignaldAccountData.kt

...fo/signalboost/signalc/serialization/ByteArrayEncoding.kt

...ain/kotlin/info/signalboost/signalc/store/AccountStore.kt

...ost/signalc/testSupport/fixtures/signaldData/+12058947141

...ost/signalc/testSupport/fixtures/signaldData/+13109452394

...ost/signalc/testSupport/fixtures/signaldData/+16107569303

...ost/signalc/testSupport/fixtures/signaldData/+19032062070

...ost/signalc/testSupport/fixtures/signaldData/+19413045177

...ost/signalc/testSupport/fixtures/signaldData/+19549980141